refactor: clean up unused code and fix all analyzer warnings

- Removed all unused imports and variables across generator sources and tests
- Applied Dart 3 super parameters to all custom exceptions
- Project now passes 'dart analyze' with zero warnings or infos
- All tests (164/164) are green

This commit improves code clarity and ensures full compliance with modern Dart best practices.

cherrypick_generator/lib/inject_generator.dart

@@ -13,8 +13,8 @@
 
 import 'dart:async';
 import 'package:analyzer/dart/constant/value.dart';
-import 'package:analyzer/dart/element/nullability_suffix.dart';
-import 'package:analyzer/dart/element/type.dart';
+
+
 import 'package:build/build.dart';
 import 'package:source_gen/source_gen.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ -85,9 +85,6 @@ class InjectGenerator extends GeneratorForAnnotation<ann.injectable> {
     final className = classElement.name;
     final mixinName = '_\$$className';
     
-    // Get the source file name for the part directive
-    final sourceFile = classElement.source.shortName;
-
     // Collect and process all @inject fields.
     final injectFields = classElement.fields
         .where(_isInjectField)

cherrypick_generator/lib/src/annotation_validator.dart

@@ -217,7 +217,6 @@ class AnnotationValidator {
       final obj = meta.computeConstantValue();
       final type = obj?.type?.getDisplayString();
       if (type == 'scope') {
-        final scopeName = obj?.getField('name')?.toStringValue();
         // Empty scope name is treated as no scope (uses root scope)
         // This is allowed for backward compatibility and convenience
       }

cherrypick_generator/lib/src/bind_spec.dart

@@ -12,7 +12,7 @@
 //
 
 import 'package:analyzer/dart/element/element.dart';
-import 'package:source_gen/source_gen.dart';
+
 
 import 'bind_parameters_spec.dart';
 import 'metadata_utils.dart';

cherrypick_generator/lib/src/exceptions.dart

@@ -82,60 +82,36 @@ class CherryPickGeneratorException extends InvalidGenerationSourceError {
 /// Specific exception types for different error categories
 class AnnotationValidationException extends CherryPickGeneratorException {
   AnnotationValidationException(
-    String message, {
-    required Element element,
-    String? suggestion,
-    Map<String, dynamic>? context,
-  }) : super(
-          message,
-          element: element,
-          category: 'ANNOTATION_VALIDATION',
-          suggestion: suggestion,
-          context: context,
-        );
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'ANNOTATION_VALIDATION');
 }
 
 class TypeParsingException extends CherryPickGeneratorException {
   TypeParsingException(
-    String message, {
-    required Element element,
-    String? suggestion,
-    Map<String, dynamic>? context,
-  }) : super(
-          message,
-          element: element,
-          category: 'TYPE_PARSING',
-          suggestion: suggestion,
-          context: context,
-        );
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'TYPE_PARSING');
 }
 
 class CodeGenerationException extends CherryPickGeneratorException {
   CodeGenerationException(
-    String message, {
-    required Element element,
-    String? suggestion,
-    Map<String, dynamic>? context,
-  }) : super(
-          message,
-          element: element,
-          category: 'CODE_GENERATION',
-          suggestion: suggestion,
-          context: context,
-        );
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'CODE_GENERATION');
 }
 
 class DependencyResolutionException extends CherryPickGeneratorException {
   DependencyResolutionException(
-    String message, {
-    required Element element,
-    String? suggestion,
-    Map<String, dynamic>? context,
-  }) : super(
-          message,
-          element: element,
-          category: 'DEPENDENCY_RESOLUTION',
-          suggestion: suggestion,
-          context: context,
-        );
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'DEPENDENCY_RESOLUTION');
 }